Orthosis for deformity correction

ABSTRACT

Disclosed are systems and methods of correction of spinal deformity that overcome current limitations by utilizing a dynamic, multi-segment torso orthosis that allows motion during wear. The disclosed embodiments utilize a series of elastically coupled segments that conform to the circumference of the torso of a patient. Adjustable elastic coupling mechanisms are utilized to create and alter forces and moments that are applied to the torso through the segments. These elastic coupling mechanisms also allow each circumferential segment to move relative to the other segments giving the brace dynamic capability.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/406,999, filed May 8, 2019, is a continuation of U.S. patentapplication Ser. No. 14/598,543, filed Jan. 16, 2015, which is basedupon and claims the benefit of U.S. Provisional Application No.61/928,709, filed Jan. 17, 2014, the entire disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

Adolescent Idiopathic Scoliosis (AIS) is an unnatural curvature of thespine that affects 2-3% of the population. Onset of this disease istypically around 10 years of age and is commonly detected (in the UnitedStates) in school screenings. The severity of the deformity is measuredwith the Cobb angle, the inside angle formed by the two most tiltedvertebrae. The minimum Cobb angle for a diagnosis of IAS is 10 degrees.While many think of scoliosis as a curvature in the coronal plane,scoliosis can be a complex three-dimensional deformity often involvingsagittal curves and rotational deformity in the axial plane.

The natural history of the disease is that many children will havecurves of 10-20 degrees that remain static. Such an amount of curvaturerarely requires treatment. The remainder of children with scoliosis havecurves that continue to progress. Once the patient hits skeletalmaturity, their curve will cease to progress if the Cobb angle measuresless than 40 degrees. Curves with a Cobb angle of 40 degrees andgreater, typically continue to progress.

Treatment for scoliosis is typically observational when curves are lessthan 25 degrees. Once curves reach 25 to 30 degrees of Cobb angle thepatient is braced in an attempt to slow or halt progression of thecurve. Curves that progress to 40 degrees or more are treated surgicallywith a spinal fusion.

Clinical studies have discovered two requirements for success in bracetreatment: brace wear for 20 hours a day or more and acute correction ofthe scoliotic curve of at least 50% at brace application.

The current state of the art (standard of care) in bracing is a rigidfull-torso brace known as a thoracolumbar-sacral orthosis (TLSO). Thisis typically a thermoplastic shell that is custom molded to thepatient's torso with modifications that are intended to reduce thecurvature through contact forces. These braces may have some effect inhalting the progression of the curvature when worn comprehensively(often more than 20 hours per day) through the treatment period. Oftenthese patients will be prescribed a brace for four or more years.

SUMMARY OF THE INVENTION

An embodiment of the present invention may therefore comprise: a systemfor externally applying corrective force to a vertebral column of apatient comprising: a plurality of ring segments that each conform tothe circumference of the torso of a patient and are positioned in aspaced, substantially coaxial configuration about a vertical axis; oneor more adjustable coupling mechanisms elastically coupled betweenadjacent ring segments comprising; at least one elastic member securedand adjustably fixated at a proximal end to a drive unit, the drive unitthat is rigidly secured to the ring; at least one receiver rigidlymounted on an adjacent circumferential ring in a substantially coplanararrangement that engages a distal end of each elastic member and allowslimited axial and lateral motion while inhibiting transverse motionthereby translating a transverse or rotational force between theadjacent circumferential ring segments.

An embodiment of the present invention may also comprise: a system forexternally applying corrective force to a vertebral column of a patientcomprising: a plurality of ring segments that each conform to thecircumference of the torso of a patient and positioned in a spaced,substantially coaxial configuration about a vertical axis; one or moredorsal adjustable coupling mechanisms elastically coupled betweenadjacent ring segments comprising; at least one elastic member securedand adjustably fixated at a proximal end to a dorsal drive unit, thedorsal drive unit that is rigidly secured to a dorsal portion of thering segment; and, at least one dorsal receiver rigidly mounted to adorsal portion of an adjacent circumferential ring in a substantiallycoplanar arrangement that engages a distal end of each elastic memberand allows limited motion in a lateral and sagittal plane whileinhibiting front-to-back motion in a transverse plane therebytranslating a transverse or rotational force between the adjacentcircumferential ring segments; a lateral adjustable coupling mechanismelastically coupled between adjacent ring segments comprising; at leastone elastic member secured and adjustably fixated at a proximal end to alateral drive unit, the lateral drive unit that is rigidly secured to alateral portion of the ring segment; and, at least one lateral receiverrigidly mounted to a lateral portion of an adjacent said circumferentialring in a substantially coplanar arrangement that engages a distal endof each elastic member and allows limited motion in a sagittal andlateral plane while inhibiting side-to-side motion in a transverse planethereby translating a transverse or rotational force between theadjacent circumferential ring segments.

An embodiment of the present invention may also comprise: a method ofexternally applying corrective force to a vertebral column of a patientcomprising: placing a plurality of ring segments in a spaced,substantially coaxial configuration about a vertical axis on the torsoof a patient such that each ring conforms to the circumference of thetorso; securing and adjustably fixating a proximal end of at least oneelastic member to a drive unit, the drive unit that is rigidly securedto the ring; coupling adjacent ring segments by engaging a distal end ofeach elastic member with at least one receiver that is rigidly mountedon an adjacent ring in a substantially coplanar arrangement; allowinglimited axial and lateral motion between the adjacent rings; inhibitingtransverse motion between the adjacent rings; and translating transverseor rotational force between the adjacent ring segments to facilitate acorrective force on the vertebral column of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 illustrates an isometric view of an embodiment of an orthosis forcorrection of spinal deformity.

FIG. 2 illustrates an isometric view of an embodiment of acircumferential ring utilized in an orthosis for correction of spinaldeformity.

FIG. 3 illustrates a top plan view of an embodiment of a circumferentialring with receiver mechanisms utilized in an orthosis for correction ofspinal deformity.

FIG. 4 illustrates an embodiment of an elastic member utilized in anorthosis for correction of spinal deformity.

FIG. 5 illustrates an embodiment of an axle utilized in an orthosis forcorrection of spinal deformity.

FIG. 6 illustrates an embodiment of a worm gear utilized in an orthosisfor correction of spinal deformity.

FIG. 7 illustrates a cross-sectional side view of an embodiment of adrive mechanism and receiver section utilized in an orthosis forcorrection of spinal deformity.

FIG. 8 illustrates an isometric view of an embodiment of an adjustablecoupling mechanism on the form of a dual drive mechanism and receiversection utilized in an orthosis for correction of spinal deformity.

FIG. 9 illustrates an isometric view of an embodiment of an adjustablecoupling mechanism on the form of a single drive mechanism and receiversection utilized in an orthosis for correction of spinal deformity.

FIG. 10 is a diagram showing the physical principals of elasticdeflection of a cantilever beam.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible to embodiment in many differentforms, it is shown in the drawings, and will be described herein indetail, specific embodiments thereof with the understanding that thepresent disclosure is to be considered as an exemplification of theprinciples of the invention and is not to be limited to the specificembodiments described.

The rigid body braces mentioned above have many limitations. Reductionforces can be inconsistent or incorrect from ineffective brace forming,patient growth, changes in posture or insufficient strap tension.Currently there are no standard methods to adjust braces to provide theadequate reduction forces.

Using a conventional rigid brace, only acute correction can be achieved.Once tissue remodeling or growth occurs, the reduction forcesimmediately drop. In addition to questionable effectiveness of reduction(based upon clinical results), compliance is a major issue in bracetreatment. Lack of compliance can come from pain, discomfort andcosmetic/lifestyle reasons. Many patients who are compliant, losesignificant muscle tone from the lack of motion during the treatmentperiod.

As shown in FIG. 1 , an embodiment of an orthosis for correction ofspinal deformity illustrates the disclosed system that overcomes thecurrent limitations by utilizing a dynamic, multi-segment torso bracethat allows motion during wear. Similar in theory to orthodonticmethods, which utilize the application of forces to reposition teeth,the disclosed system exploits the physiological response of a body overtime to constant force, called tissue remodeling. The disclosedembodiments illustrate a series of segments that conform to thecircumference of the torso of a patient. Each of these segments iselastically coupled to an adjacent segment or segments. An adjustableelastic coupling mechanism is capable of creating and altering forcesand moments that are applied to the torso through the segment. Thiselastic coupling mechanism also allows each circumferential segment tomove relative to the other segments giving, the brace dynamiccapability.

The embodiment of FIG. 1 shows a series of interlinked circumferentialrings 102. These circumferential rings 102 are typically a plurality ofsemi rigid bands that circumscribe the torso of the patient in theregion from the sub-axillary thorax to the pelvis, superior of thegreater trochanter. Each ring 102 is connected to at least one otherring in the plurality by at least one elastic member 110. Typically, arod made of semi-rigid metal, polymer, graphite, carbon fiber, syntheticfiber, para-aramid synthetic fiber, Kevlar, fiberglass, or the like, orany combination thereof may be utilized. Materials utilizing shapememory and superelasticity (also called pseudoelasticity) such asnitinol or the like may also be utilized. In the embodiment disclosed onFIG. 1 , a pair of elastic members 110, like the one shown in FIG. 4 ,physically communicates with each circumferential ring 102. In thisembodiment, the inferior most circumferential ring 102 fixates theproximal (inferior) end of the pair of elastic members 110 on the dorsalportion of the ring utilizing retention hardware, which is in thiscircumstance, an axle 112. The axle 112, detailed in FIG. 5 , contains athrough-hole 114 that facilitates insertion and fixation of the elasticmember 110, while maintaining a perpendicular (coincidental) orientationof the longitudinal axis of the axle 112 and the elastic member 110.

The axle 112 is inserted into a drive unit 116 that contains fixedbearing mounts 118 for each axle 112. These bearing mounts 118 securethe position of the axle 112 while allowing a limited amount ofrotation. The rotation and orientation of the axle 112 may be fixatedand positioned within the bearing mount 118 utilizing a set of gears. Inthis example, the axle 112 contains a toothed portion (gear 120) on theouter surface of the axle shaft 124 that meshes with a worm gear 126(see FIG. 6 ) mounted and fixated to rotate within a bearing mount 118.In this embodiment, the axle 112 is inserted between a pair of fixedbearing mounts 118 and held in place with endcaps 124 that fix theposition of the axle 112 within mounts while allowing limited rotation.The rotation of the axle 112 is precisely fixated and positionedutilizing the worm gear 126 meshing with the axle shaft gear 120. Thus,rotation of the worm gear 126 produces an alteration of the axle 112rotation, which produces a force tending to change the orientation ofthe fixated end of the elastic member 110.

The elastic member 110 extends to, and communicates with, the nextadjacent circumferential ring 102 and is accepted by a receiver (in thisexample a dorsal receiver 104). The dorsal receiver 104 may comprise aconstraining notch that restricts movement of the elastic member 110 incertain directions thereby transmitting force, while allowing motion inother directions, thereby allowing movement.

In the embodiment illustrated in FIG. 1 , the opening in the dorsalreceiver 104 that the elastic member 110 is inserted into is asemi-rectangular notch. This allows movement between the adjacent rings102 in the longitudinal direction of the elastic member 110, whilerestricting motion in the lateral direction of the short side of therectangular notch, and limiting the motion in the lateral direction ofthe long side of the rectangular notch (perpendicular to the shortside).

Because of the complex 3-dimensional nature of spinal deformity,successful reduction of the curve relies upon a combination of forcesand moments applied to the torso. Because of the need for de-rotation ofthe rib cage when axial deformity is present, each segment of theembodiments conforms to the circumference of the patient's torso withoutsignificant slippage or deformation. This rigid segment ensures that thesystem provides forces to counter the deformation rotation and providethe necessary reduction forces and moments. The illustration of FIG. 1 ,details the multi-segmented orthosis as a series of interlinkedcircumferential rings 102 that are positioned in a spaced, substantiallycoaxial configuration about a central vertical axis 101 extendingcentrally perpendicular to the rings 102, and typically oriented in thetransverse plane 107 as shown.

Successful reduction of complex spinal deformity relies upon placingcomplex forces on the torso. The disclosed embodiment allows thecircumferential rings 102 to be custom sized to a patient for a snug butcomfortable fit. The individual sections of the spine may be manipulatedby the force that the ring 102 places on the torso. As shown in FIG. 1 ,the inferior most circumferential ring 102 comprises a drive unit 106that includes the proximal mounting and adjustment surfaces for theelastic members 110. These mechanisms, in combination with the receiversection (e.g., dorsal receiver 104 and/or lateral receiver 111),facilitate a transfer of force form orthotic section to section, andthus, spinal section to section.

As shown further in FIGS. 7-9 , force may be communicated from theattached ring 102 to the bearing mounts 118 of the drive unit 116. Thebearing mounts fixate the axle 112, which in turn fixates the elasticmember. The force communicated between two adjacent ring 102 sections isadjusted in the sagittal plane 105 by setting the position angle of thetwo elastic members 110 and may facilitate a dorsal force communicatedto the patient by pulling one ring away from the vertical axis 101 andlateral plane 103, as well as being able to facilitate a ventral forcein the patient by pulling one ring towards the vertical axis 101 andlateral plane 103. Since this adjustable coupling mechanismcommunicating in a drive and receiver section 200 on the dorsal receiver104 may be set to push on one side while the other pulls,anti-rotational forces may be applied between ring 102 segments.

Lateral adjustments may be facilitated utilizing another adjustablecoupling mechanism in the form of a lateral receiver 111 that isutilized to apply force in the sagittal plane 105 of the wearer. Theseforces can also either push or pull the spine into proper alignment.When the lateral forces are combined with the dorsal and ventral forces(positive and/or negative), a system that allows a wide variety oftherapeutic spinal forces is accomplished, including anti-rotation.Front-to-back (dorsal-ventral) and side-to-side (lateral and rotation)disorders may all be treated with a single customized, adjustable forceorthosis. Complex maladies such as scoliosis (including de-rotation) maybe treated and corrected utilizing the disclosed system as well as other(typically less complex) spinal disorders such as lordosis and kyphosis.These forces may be applied to the entire length of the movable spine orthey may be segmented individually to the cervical, thoracic, or lumbarregions of the spine. By allowing the elastic members 110 to move intheir axial direction within the receiver (104, 111), the wearer isafforded some movement and freedom in certain directions. The size andorientation of the receiver (104, 111) and the length and width of thereceiving slot determine the amount of movement that the orthosisaffords the wearer. This too is highly variable and customizable.

The adjustable coupling mechanism shown in FIG. 7 illustrates a sideview of a single elastic member 110 mounted to a drive unit 116utilizing sets of bearing mounts 118. The lateral receiver 111 ismounted on an adjacent circumferential ring 102 section in asubstantially coplanar orientation about a sagittal plane 105. Where thedrive unit 116 and lateral receiver 111 are shown coplanar, it is withinthe scope of the disclosure that variations in the anatomy of thewearer's torso may place the orientation in a substantially coplanarorientation due to spinal malcurvature, misalignment, disorder, traumaor other anatomical variation. By setting the position of the axle 112utilizing, for instance, a worm gear mechanism, a push and/or pull ofthe elastic member 110 in the sagittal plane 105 is realized. The forceangle 214 (in this example shown as a pull force wanting to create thedeflection axis 216) facilitates a force that is precisely adjustable inmagnitude and direction to perform a variety of corrective actions.

As illustrated in FIG. 7 , it is apparent that the elastic member 110 isacting as a classic spring beam deflection model with a beam of length(L) is fixed at one end (by the drive unit 116) and is deflected by aforce (F) by an amount (6) (see FIG. 10 (a)), where the deflection6=FL3//3EI, and E is the Young's Modulus of the beam, and I is themoment of inertia of the beam. Utilizing these principals, the beam maybe tailored to a patient's specific corrective need, in the sense thatif more or less force is needed, or preferential forces need to beutilized to provide optimal correction, the beam properties may beeasily changed. For example, a beam with a round cross-section may beutilized when no preferential forces are needed in the lateral orsagittal plane, but if the patient were in need of correction wherepreferential forces in either the lateral or sagittal plane wouldoptimize their outcome, a rectangular (or other nonsymmetrical) shapemay be utilized.

Moment of inertia Moment of inertia for round section for rectangularsection I = Πr⁴/4 = Πd⁴/64 I = bh³/12 where r and d are where h is thedimension the radius and in the plane of bending, diameter respectivelyi.e. in the axis in which the bending moment is applied

In this example, by adjusting the height (h) and width (b)characteristics of the elastic member 110 (beam), the forces displacedfrom ring segment 102 to ring segment may be varied. Whereas, the aboveshows a spring beam depicted as a cantilever beam, the force F isactually translated to the adjacent ring segment 102 and acts more as asimply supported beam, for the beam is fixed at one end and simplysupported at the other (see FIG. 10 (b)). This too is a simplificationfor demonstrative purposes, because the force produced by the couplingof the adjacent ring segments 102 is transmitted as a corrective forceto the patient.

The adjustable coupling mechanism shown in FIG. 8 utilizes a pair ofelastic members 110 mounted to a drive unit 116 utilizing sets ofbearing mounts 118 offset from the longitudinal axis 202 by an offsetangle 204. The dorsal receiver 104 is mounted on an adjacent ring 102section (as depicted in FIG. 1 for example) in a substantially coplanarorientation about a lateral plane 103. Where the drive unit 116 anddorsal receiver 104 are shown coplanar, it is within the scope of thedisclosure that variations in the anatomy of the wearer's torso mayplace the orientation in a substantially coplanar orientation due tospinal malcurvature, misalignment, disorder, trauma or other anatomicalvariation. By setting the position of the axle 112, a push and/or pullof the pair of elastic members 110 in the lateral plane 103 is realized.The offset angle 204 facilitates a force that is precisely adjustable inmagnitude and direction to perform a variety of corrective actions.

The adjustable coupling mechanism shown in FIG. 9 illustrates anisometric view of the single lateral receiver 111 and elastic member 110mounted to a drive unit 116 utilizing sets of bearing mounts 118. Thedorsal receiver 104 is mounted on an adjacent ring 102 section (asdepicted in FIG. 7 for example) in a substantially coplanar orientationabout a sagittal plane 105.

Depending upon the type, degree and complexity of the mal-curvature ofthe spine, two or more rings 102 may be combined to customize anorthotic to resist and correct such disorders.

In an instance where the curvature disorder is small or localized, fewerring segments may be necessary, and in a situation where the spine issignificantly deformed, a large number of rings 102 may be utilized. Thedesign also allows for smaller ring segments to be positioned beyond thetorso extending to the head, leg, arm, shoulder or neck, if the needexists. With this high degree of variability, the orthosis may also haveapplication as a mobility limiting splint to immobilize certainmovements after surgery or trauma.

The Hooke's (spring force constant) or Young's Modulus of the elasticmember 110 may also be varied to provide additional restraint orflexibility between the circumferential rings 102. In a situation wherea small adolescent patient needs correction, a more flexible rod may bebeneficial, whereas a stiffer elastic member 110 may be utilized for alarger, heavier adult patient or in a situation where greaterimmobilization is warranted. Various combinations of stiffness withinthe elastic members 110 may be combined to tailor an orthotic to anindividual patient for the intended outcome. This variability instiffness may be implemented from ring section to ring section, or evenwithin the individual drive and receiver sections 200, thereby providingyet additional customization for the wearer.

With the wide variability the system affords, precise forces may beplaced upon the spine of the wearer. As the body responds to theseforces, tissue remodeling and/or growth occur and these forcesimmediately drop. The disclosed system allows for easy readjustment ofthe applied forces to correct and re-align the spinal column andexploits the physiological response of a body over time to constantforce. The patient may be initially evaluated and measured, thecorrective geometry determined, and a custom orthosis may be created toprecisely fit the body and corrective/stabilization needs of the wearer.With the ease of adjustment of the forces that the orthosis applies, thewearer may be refitted or adjusted on a routine, even short term basissuch as weekly, bi-weekly or monthly depending upon the spinal response.

Successful reduction of complex spinal deformity also relies on usingfixed reference endpoints that are not affected by deformity. In oneembodiment of the disclosed orthotic system, the shoulders and pelvicgirdle may serve as these reference endpoints.

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andother modifications and variations may be possible in light of the aboveteachings. The embodiment was chosen and described in order to bestexplain the principles of the invention and its practical application tothereby enable others skilled in the art to best utilize the inventionin various embodiments and various modifications as are suited to theparticular use contemplated. It is intended that the appended claims beconstrued to include other alternative embodiments of the inventionexcept insofar as limited by the prior art.

1. (canceled)
 2. A system for externally applying corrective force to avertebral column of a patient comprising: a plurality of separate ringsegments that are each adapted to conform to the circumference of thetorso of a patient and are positioned in a spaced, substantially coaxialconfiguration about a vertical axis, said plurality of ring segmentsincluding at least an inferior terminal ring segment, a superiorterminal ring segment, and at least one intermediate ring segmentdisposed between the inferior terminal ring segment and the superiorterminal ring segment; at least one adjustable coupling mechanism on adorsal surface of each intermediate ring segment and of a first of thetwo terminal ring segment; at least one dorsal receiver rigidly mountedon a dorsal surface of each intermediate ring segment and on a second ofthe two terminal ring segments; at least one elastic member extendingfrom each adjustable coupling mechanism on a ring segment to the dorsalreceiver on a different ring segment; wherein each adjustable couplingmechanism is configured to rotate and to adjustably fixate an end of theattached elastic member so that the elastic member applies a force tothe dorsal receiver on the adjacent ring segment, wherein the forcerotates the adjacent ring about the vertical axis.
 3. The system ofclaim 2, further comprising an adjustable coupling mechanisms positionedon a lateral surface of one of the superior or inferior terminal ringsegment and on each intermediate ring segments and is configured torotate and fixate an end of an attached elastic member to deflect anaxis of the attached elastic member to apply a force on a lateralreceiver on an adjacent ring segment in a sagittal plane.
 4. The systemof claim 3 wherein each adjustable coupling mechanism is configured toapply a rotational force, to the end of the respective elastic memberand to fix a rotational position of the end of the respective elasticmember after rotation.
 5. The system of claim 3 wherein each adjustablecoupling mechanism comprises: an axle secured on opposing ends by abearing mount; wherein said proximal end of said elastic member isconnected to the axle perpendicularly to a longitudinal axis of theaxle; and an adjustable fixator that allows said axle to be rotated foradjustment and fixated at a specific position thereby allowing a fixedpositioning of said elastic member with respect to adjustable couplingmechanism.
 6. The system of claim 5 wherein axle is secured directly tothe proximal end of the elastic member and the fixator comprises a gearconfigured to rotationally drive the axle.
 7. The system of claim 2wherein each elastic member comprises a spring beam.
 8. The system ofclaim 2 wherein each elastic member is comprised of material chosen fromthe group consisting of a semi-rigid metal, a superelastic metal, ashape memory alloy, a polymer, graphite, synthetic fiber, para-aramidsynthetic fiber, carbon fiber, fiberglass, and iii triol.
 9. The systemof claim 2 wherein each adjustable coupling mechanism unit is positionedcloser to said longitudinal axis than is each dorsal receiver such thatsaid elastic members extending between the adjustable couplingmechanisms and the dorsal receivers are placed at an offset angle tosaid longitudinal axis.
 10. The system of claim 2 wherein each dorsalreceiver allows limited motion in a lateral and sagittal plane whileinhibiting front-to-back motion in a transverse plane therebytransmitting a transverse or rotational force between said adjacent ringsegments.
 11. The system of claim 2, wherein each receiver comprises aslot sized configured to allow a free end of the elastic member limitedmotion in a lateral and sagittal plane while inhibiting front-to-backmotion in a transverse plane.
 12. The apparatus of claim 11, wherein thelength and width of the slot are configured to be varied.
 13. Anapparatus for adjustably coupling two or more segments of a wearabledevice configured to restrict a movement of a user, the apparatuscomprising: at least one drive unit adjustably mounted to a firstsegment of the two or more segments, wherein the drive unit isconfigured to rotate and to adjustably fixate one end of elastic member;a receiver adjustably mounted to a second segment wherein the first andsecond segments are separate from each other and are spaced-apart alonga vertical axis of the two or more segments, wherein the receiver isconfigured to receive a second end of the elastic member such that thedriver and the receiver are mechanically coupled by the elastic membersuch that the elastic member applies a force to the receiver on thesecond segment, wherein the force rotates the second segment about thevertical axis; and wherein the receiver is configured to determine adegree of restriction of the movement of the user.
 14. The apparatus ofclaim 13, wherein each drive unit further comprises: an axle secured onopposing ends by a bearing mount; wherein said proximal end of saidelastic member is connected to the axle perpendicularly to alongitudinal axis of the axle; and an adjustable fixator that allowssaid axle to be rotated for adjustment and fixated at a specificposition thereby allowing a fixed positioning of said elastic memberwith respect to the drive unit.
 15. The apparatus of claim 14, whereinthe bearing mount is configured to secure the position of the axle whileallowing a limited amount of rotation.
 16. The apparatus of claim 14,wherein the axle comprises a toothed portion on the outer surface of theaxle shaft configured to couple to a worm gear configured to preciselyfixate the rotation of the axle.
 17. The apparatus of claim 15, whereinrotation of the worm gear is configured to adjust the rotation of theaxle and produce a force tending to change the orientation of thefixated end of the elastic member.
 18. The apparatus of claim 13,wherein the first end of the elastic member is inserted into the driveunit and held in place with endcaps configured to fix the position ofthe first end of the elastic member within the drive unit.
 19. Theapparatus of claim 13, wherein the receiver is configured to fix thesecond end of the elastic member.
 20. The apparatus of claim 13, whereinthe receiver is configured as a slot to receive the at least one elasticmember.
 21. The apparatus of claim 20, wherein the length and width ofthe receiving slot is configured to control the amount of movement ofthe user.
 22. The apparatus of claim 20, wherein the length and width ofthe receiving slot are configured to be varied.